Hi and welcome, I'm glad you found this site. It has been such an enormous help to me during some of my worst times and I'm sure you'll find it to be a great support for you as well. I don't have diabetes, so I can't speak on that subject, but I've had panic/anxiety disorder and agoraphobia for 18 years. I think it's pretty common for anxiety to come on quickly, especially if you are obsessing over a worry as you mentioned. The worrying sensitizes your nerves and
opens the door to anxiety.
Freezing is right about using cbt, it is the best way to go. I take xanax as well and that does help, but for me the cbt is much more helpful as the xanax only lasts so long. I also always recommend reading books by Claire Weekes, she discusses anxiety disorder in such an easy to understand way and offers a cbt method that I use regularly. I do hope that you will continue to post here, there is always someone else who is going through exactly what you are and that is an amazing comfort!